ATP has pKa values of 0.9, 1.5, 2.3, and 7.7; ADP has pKa values of 0.9, 2.8,

Question:

ATP has pKa values of 0.9, 1.5, 2.3, and 7.7; ADP has pKa values of 0.9, 2.8, and 6.8; and
phosphoric acid has pKa values of 1.9, 6.7, and 12.4.
Do the calculation showing that at pH 7.3:
a. The charge on ATP is - 3.3
b. The charge on ADP is - 2.8
c. The charge on phosphate is - 1.1